Folk Medicine

Publication Title: 
Bulletin of the World Health Organization

In-vitro drug sensitivity tests were performed on Philippine isolates of Plasmodium falciparum between 1991 and 1993, using the radioisotope microdilution method. The success of the tests varied significantly with the level of parasitaemia, the source of the strains, the period that elapsed before culturing, and the detectable concentrations of antimalarials in the blood. There was a significant positive correlation between the IC50 values for chloroquine and artesunate and the level of chloroquine in the blood before testing.

Author(s): 
Bustos, M. D.
Gay, F.
Diquet, B.
Publication Title: 
Bulletin of the World Health Organization

A randomized comparative trial of the pharmacokinetics and pharmacodynamics of oral doses of mefloquine and of mefloquine in combination with artesunate was carried out on 20 Thai male patients with acute, uncomplicated falciparum malaria. The patients were randomized to receive either mefloquine alone (8 patients; 1250 mg of mefloquine--initial dose, 750 mg; followed 6 hours later by 500 mg), or in combination with oral artesunate (12 patients--initial dose, 200 mg of artesunate; followed by 750 mg and 500 mg of mefloquine 6 hours and 12 hours later, respectively).

Author(s): 
Karbwang, J.
Na Bangchang, K.
Thanavibul, A.
Back, D. J.
Bunnag, D.
Harinasuta, T.
Publication Title: 
Bulletin of the World Health Organization

In Thailand Plasmodium falciparum malaria is highly resistant to available antimalarials. Investigations on the efficacy of existing antimalarials and of alternative drugs are urgently needed. Artesunate has been shown to be effective against falciparum malaria, but is associated with a high recrudescence rate. We have carried out a comparative clinical trial of the standard regimen of quinine + tetracycline versus oral artesunate at a 700-mg total dose given over 5 days to patients with acute uncomplicated falciparum malaria.

Author(s): 
Karbwang, J.
Na-Bangchang, K.
Thanavibul, A.
Bunnag, D.
Chongsuphajaisiddhi, T.
Harinasuta, T.
Publication Title: 
The Journal of Clinical Investigation

Plasmodium falciparum infecting hemoglobin (Hb)H and/or Hb Constant Spring erythrocytes has higher resistance to artemisinin in vitro than when infecting normal erythrocytes. This is due to low drug accumulation of infected erythrocytes resulting from competition with uninfected variant erythrocytes, which have a higher accumulation capacity than genetically normal cells. Drug accumulation of the parasite was shown to be saturable and dependent on metabolic energy.

Author(s): 
Kamchonwongpaisan, S.
Chandra-ngam, G.
Avery, M. A.
Yuthavong, Y.
Publication Title: 
British Journal of Clinical Pharmacology

1. The pharmacokinetics of artemether were investigated (a) in six healthy male Thai volunteers after single 200 mg oral doses and (b) in eight male Thai patients with acute uncomplicated falciparum malaria after an initial 200 mg oral dose followed by 100 mg at 12 h then 100 mg daily for 4 days. 2. In the healthy subjects, median (range) maximum plasma concentrations of artemether of 118 (112-127) ng ml-1 were reached at 3 (1-10) h. Thereafter, drug concentrations declined monoexponentially with a median (range) t1/2.z of 3.1 (1.0-9.6) h.

Author(s): 
Na Bangchang, K.
Karbwang, J.
Thomas, C. G.
Thanavibul, A.
Sukontason, K.
Ward, S. A.
Edwards, G.
Publication Title: 
Antimicrobial Agents and Chemotherapy

The in vitro effect of the following antimicrobial agents on Toxoplasma gondii tachyzoites were studied: artemisinin ether (arteether), cycloguanil hydrochloride (cycloguanil), mefloquine, primaquine phosphate, and quinine sulfate, as well as the calcium channel blocker verapamil and the calmodulin inhibitor trifluoperazine hydrochloride. Arteether at > or = 0.5 micrograms/ml and cycloguanil at > or = 1.0 micrograms/ml inhibited T. gondii in vitro. Cycloguanil (2.5 micrograms/ml) combined with a noninhibitory concentration of sulfadiazine (25 micrograms/ml) inhibited T.

Author(s): 
Holfels, E.
McAuley, J.
Mack, D.
Milhous, W. K.
McLeod, R.
Publication Title: 
Antimicrobial Agents and Chemotherapy

The sesquiterpene endoperoxide antimalarial agents arteether and artemether have been reported to cause neurotoxicity with a discrete distribution in the brain stems of rats and dogs after multiple doses. The nature and distribution of the brain lesions suggest a specific neuronal target, the identity of which is unknown.

Author(s): 
Wesche, D. L.
DeCoster, M. A.
Tortella, F. C.
Brewer, T. G.
Publication Title: 
Antimicrobial Agents and Chemotherapy

The endoperoxides are a new class of antimalarial agents, of which artemisinin (qinghaosu) is the prototype. We have previously shown that artemisinin is capable of alkylating proteins in model reactions. In the present study, we showed that when Plasmodium falciparum-infected erythrocytes are treated with a radiolabeled antimalarial endoperoxide, either arteether, dihydroartemisinin, or Ro 42-1611 (arteflene), the radioactivity is largely coverted into a form which can be extracted with sodium dodecyl sulfate (SDS).

Author(s): 
Asawamahasakda, W.
Ittarat, I.
Pu, Y. M.
Ziffer, H.
Meshnick, S. R.
Publication Title: 
Zhongguo Yao Li Xue Bao = Acta Pharmacologica Sinica

Artemether (Art, beta-methyl ether of artemisinin) first synthesized by Shanghai Institute of Materia Medica, Chinese Academy of Sciences, is effective against not only malaria but also schistosomiasis. When rabbits infected with Schistosoma japonicum cercariae for 7 d were treated ig with Art 10 mg.kg-1, the total worm reduction rates were 74.6-76.7%. If Art (10 mg.kg-1) was given once weekly after the first treatment for 3-4 times, the total worm reduction rate was > 98%, and most of the rabbits were free from female worms.

Author(s): 
Xiao, S. H.
You, J. Q.
Mei, J. Y.
Jiao, P. Y.
Publication Title: 
Zhongguo Yao Li Xue Bao = Acta Pharmacologica Sinica

Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm, was used to study the correlations between the physicochemical properties and the in vitro activities of a series of ether and ester analogs of artemisinin. Four alignment models were used in the CoMFA investigation. The correlations derived from CoMFA analysis with the four alignments proved all to have good predictive values.

Author(s): 
Jiang, H. L.
Chen, K. X.
Wang, H. W.
Tang, Y.
Chen, J. Z.
Ji, R. Y.

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